Shampoo compositions comprising various combinations of detersive surfactants and conditioning agents, especially silicone conditioning agents, are known in the art and are commercially available. Many of these compositions have been found to provide excellent hair cleansing and conditioning performance. For example, Pantene® Shampoo Plus Pro-Vitamin Conditioner-in-One formulas which contain anionic surfactants, a cationic polymer and silicone conditioning agents provide excellent cleaning, conditioning and hair feel benefits upon application to hair.
Anti-dandruff shampoos are also well known in the art and are also commercially available. Anti-dandruff shampoos typically incorporate an anti-dandruff active and detersive surfactants. Among the preferred type of anti-dandruff agents are particulate, crystalline anti-dandruff agents, such as sulfur, selenium disulfide and heavy metal salts of pyridinethione. Soluble anti-dandruff agents, such as ketoconazole, are also known in the art.
Anti-dandruff shampoos which also provide conditioning benefits are likewise known in the art. For example, U.S. Pat. No. 5,624,666 exemplifies and claims shampoo compositions, which contain anionic surfactants, cationic polymers and zinc pyridinethione, as an anti-dandruff agent. U.S. Pat. No. 5,624,666 teaches that conditioning agents such as silicone fluids can optionally be incorporated into the compositions therein. Head & Shoulders® Dandruff Shampoo Plus Conditioner is an example of a marketed product which provides both anti-dandruff and conditioning benefits upon application of the shampoo to hair.
Nevertheless, some consumers desire a shampoo which provides a superior combination of anti-dandruff efficacy and conditioning performance versus currently marketed products. Such a superior combination of efficacy and conditioning can be difficult to achieve.
For example, one way to achieve excellent conditioning benefits is to employ a fairly high level of cationic polymer in the shampoo composition. However, the use of high levels of cationic polymer can affect the characteristics of the coacervate formed between the cationic polymer and the anionic surfactant in a manner which negatively impacts the deposition of the anti-dandruff active on the hair and scalp. Thus, it has heretofore been believed that the level of cationic polymer had to be balanced to provide the best balance of conditioning and anti-dandruff efficacy.
Also by way of example, it was previously believed that excellent anti-dandruff efficacy could be achieved by utilizing a coacervate to deposit anti-dandruff actives on the hair and scalp. Unfortunately, the use of coacervates to deposit anti-dandruff actives on the hair or scalp can negatively affect conditioning, specifically clean hair feel. In order to achieve good conditioning, the level of anti-dandruff agent could be reduced, resulting in good conditioning, but less than optimal anti-dandruff efficacy.
Applicants have now discovered, however, that, surprisingly, bioavailability and coverage of the anti-dandruff active are much more predictive of efficacy than deposition of the active on the hair or scalp. In fact, Applicants have found that, in some cases, even when an anti-dandruff active deposited very well on the hair and scalp, acceptable anti-dandruff efficacy was not achieved. Conversely, good anti-dandruff efficacy could be achieved in situations where the anti-dandruff active had good coverage and was highly bioavailable, but did not deposit superiorly to the hair or scalp. Thus, in order for a shampoo composition to provide a superior combination of anti-dandruff efficacy and conditioning compared to known shampoo compositions, it must meet certain criteria with respect to bioavailability and coverage, but it does not necessarily have to have the ability to deposit the anti-dandruff active superiorly on the hair or scalp.
Applicants have found that four requirements must be satisfied in order to provide shampoo compositions which provide a superior combination of efficacy and conditioning. Particularly, (1) bioavailability and coverage of the anti-dandruff active are important to anti-dandruff efficacy; (2) comb-ability of wet hair and (3) clean hair feel are important to the consumer perception of well-conditioned hair; and (4) the inherent ability of the anti-dandruff active to inhibit the growth of microorganisms has an impact on the anti-dandruff efficacy as well as overall consumer acceptance of the shampoo product.
Whether or not the requisite criteria are met for a given shampoo composition depends on a number of aspects of the shampoo formulation including, for example, the level and type of cationic polymer employed in the composition, the type of anti-dandruff agent employed, the amount of anionic surfactant employed, the level and type of polyalkylene glycol employed, if any, and the rheological characteristics of the coacervate.
It is an object of the present invention to provide shampoo compositions, which provide a superior combination of anti-dandruff efficacy and conditioning. It is also an object of the present invention to provide a method for cleansing and conditioning the hair. These, and other objects, will become readily apparent from the detailed description below.